I have created process with multiple instances of human task and MinaTaskServer, it works if I put empty list of parameters for creating inctances, but if I put 1 or more parameters I'll get an error - Referential integrity constraint violation.

MinaTaskServer contains task session with users: "Administrator and "mina". How to provide the list of users for a multiple instances of human task?

If you get a Referential Integrity constraint violation is that you probably are referencing an user that is not created in the human task server. If you add the Administrator user that's fine, but what about the "mina" user? that's not needed at all. I'm not sure to understand where and how are you creating multiple instances of the human task server.